Synchronization for standalone LTE broadcast

ABSTRACT

Aspects of the present disclosure relate to wireless communications and, more particularly, to synchronization for standalone long term evolution (LTE) broadcast. In one aspect, a method is provided which may be performed by a wireless device such as a user equipment (UE). The method generally monitoring, within anchor subframes occurring at a first periodicity, for synchronization signals of a first type, obtaining an indication of one or more unicast subframes scheduled to occur between anchor subframes, and obtaining an indication of one or more broadcast subframes scheduled to occur between anchor subframes.

CLAIM OF PRIORITY UNDER 35 U.S.C. § 119

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 62/304,906, filed Mar. 7, 2016, which is herein incorporated byreference in its entirety.

BACKGROUND Field of the Disclosure

Certain aspects of the present disclosure generally relate to wirelesscommunications and, more particularly, to synchronization for standalonelong term evolution (LTE) broadcast.

Description of Related Art

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, and so on. Thesesystems may be multiple-access systems capable of supportingcommunication with multiple users by sharing the available systemresources (e.g., bandwidth and transmit power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, 3rd Generation PartnershipProject (3GPP) Long Term Evolution (LTE)/LTE-Advanced systems andorthogonal frequency division multiple access (OFDMA) systems.

Generally, a wireless multiple-access communication system cansimultaneously support communication for multiple wireless terminals.Each terminal communicates with one or more base stations viatransmissions on the forward and reverse links. The forward link (ordownlink) refers to the communication link from the base stations to theterminals, and the reverse link (or uplink) refers to the communicationlink from the terminals to the base stations. This communication linkmay be established via a single-input single-output, multiple-inputsingle-output or a multiple-input multiple-output (MIMO) system.

A wireless communication network may include a number of base stationsthat can support communication for a number of wireless devices.Wireless devices may include user equipments (UEs). Machine typecommunications (MTC) may refer to communication involving at least oneremote device on at least one end of the communication and may includeforms of data communication which involve one or more entities that donot necessarily need human interaction. MTC UEs may include UEs that arecapable of MTC communications with MTC servers and/or other MTC devicesthrough Public Land Mobile Networks (PLMN), for example.

SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “DETAILED DESCRIPTION” one will understand how thefeatures of this disclosure provide advantages that include improvedcommunications between access points and stations in a wireless network.

Certain aspects of the present disclosure provide a method for wirelesscommunications performed by a wireless node such as a base station (BS).The method generally includes transmitting, within anchor subframesoccurring at a first periodicity, synchronization signals of a firsttype, providing an indication of one or more unicast subframes scheduledto occur between anchor subframes, and providing an indication of one ormore broadcast subframes scheduled to occur between anchor subframes.

Certain aspects of the present disclosure provide an apparatus forwireless communications performed by a wireless node such as a basestation (BS). The apparatus generally includes at least one processorconfigured to transmit, within anchor subframes occurring at a firstperiodicity, synchronization signals of a first type, providing anindication of one or more unicast subframes scheduled to occur betweenanchor subframes, and providing an indication of one or more broadcastsubframes scheduled to occur between anchor subframes. The apparatusalso generally includes a memory coupled with the at least oneprocessor.

Certain aspects of the present disclosure provide an apparatus forwireless communications performed by a wireless node such as a basestation (BS). The apparatus generally includes means for transmitting,within anchor subframes occurring at a first periodicity,synchronization signals of a first type, means for providing anindication of one or more unicast subframes scheduled to occur betweenanchor subframes, and means for providing an indication of one or morebroadcast subframes scheduled to occur between anchor subframes.

Certain aspects of the present disclosure provide a non-transitorycomputer-readable medium for wireless communications performed by awireless node such as a base station (BS). The non-transitorycomputer-readable medium generally includes instructions fortransmitting, within anchor subframes occurring at a first periodicity,synchronization signals of a first type, providing an indication of oneor more unicast subframes scheduled to occur between anchor subframes,and providing an indication of one or more broadcast subframes scheduledto occur between anchor subframes.

Certain aspects of the present disclosure provide a method for wirelesscommunications performed by a wireless node such as a user equipment(UE). The method generally includes monitoring, within anchor subframesoccurring at a first periodicity, for synchronization signals of a firsttype, obtaining an indication of one or more unicast subframes scheduledto occur between anchor subframes, and obtaining an indication of one ormore broadcast subframes scheduled to occur between anchor subframes.

Certain aspects of the present disclosure provide an apparatus forwireless communications performed by a wireless node such as a userequipment (UE). The apparatus generally includes at least one processorconfigured to monitor, within anchor subframes occurring at a firstperiodicity, for synchronization signals of a first type, obtain anindication of one or more unicast subframes scheduled to occur betweenanchor subframes, and obtain an indication of one or more broadcastsubframes scheduled to occur between anchor subframes. The apparatusalso generally includes a memory coupled with the at least oneprocessor.

Certain aspects of the present disclosure provide an apparatus forwireless communications performed by a wireless node such as a userequipment (UE). The apparatus generally includes means monitoring,within anchor subframes occurring at a first periodicity, forsynchronization signals of a first type, means for obtaining anindication of one or more unicast subframes scheduled to occur betweenanchor subframes, and means for obtaining an indication of one or morebroadcast subframes scheduled to occur between anchor subframes.

Certain aspects of the present disclosure provide a non-transitorycomputer-readable medium for wireless communications performed by awireless node such as a user equipment (UE). The non-transitorycomputer-readable medium generally includes instructions for monitoring,within anchor subframes occurring at a first periodicity, forsynchronization signals of a first type, obtaining an indication of oneor more unicast subframes scheduled to occur between anchor subframes,and obtaining an indication of one or more broadcast subframes scheduledto occur between anchor subframes.

Other aspects, features, and embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary aspects of the presentinvention in conjunction with the accompanying figures. While featuresof the present disclosure may be discussed relative to certain aspectsand figures below, all embodiments of the present disclosure can includeone or more of the advantageous features discussed herein. In otherwords, while one or more aspects may be discussed as having certainadvantageous features, one or more of such features may also be used inaccordance with the various aspects of the disclosure discussed herein.In similar fashion, while exemplary aspects may be discussed below asdevice, system, or method aspects it should be understood that suchexemplary aspects can be implemented in various devices, systems, andmethods

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. The appended drawingsillustrate only certain typical aspects of this disclosure, however, andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects.

FIG. 1 is a block diagram conceptually illustrating an example of awireless communication network, in accordance with certain aspects ofthe present disclosure.

FIG. 2 shows a block diagram conceptually illustrating an example of abase station in communication with a user equipment (UE) in a wirelesscommunications network, in accordance with certain aspects of thepresent disclosure.

FIG. 3 is a block diagram conceptually illustrating an example of aframe structure in a wireless communications network, in accordance withcertain aspects of the present disclosure.

FIG. 4 is a block diagram conceptually illustrating two exemplarysubframe formats with the normal cyclic prefix

FIG. 5 illustrates various components that may be utilized in a wirelessdevice, in accordance with certain aspects of the present disclosure.

FIG. 6 is a flow diagram illustrating example operations for wirelesscommunications by a base station (BS), in accordance with certainaspects of the present disclosure.

FIG. 7 is a flow diagram illustrating example operations for wirelesscommunications by a user equipment (UE), in accordance with certainaspects of the present disclosure.

FIG. 8 illustrates an example timeline for LTE standalone broadcast, inaccordance with certain aspects of the present disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

Certain aspects of the present disclosure generally relate to wirelesscommunications and, more particularly, to synchronization for standalonelong term evolution (LTE) broadcast. According to certain aspects, anLTE broadcast system eliminates synchronization capabilities based onthe primary synchronization signals (PSSs) and secondary synchronizationsignals (SSSs). Due to the lack of PSS and SSS in an LTE broadcastsystem, synchronization issues may exist. Thus, aspects of the presentdisclosure provide techniques for alieving the issue withsynchronization in a standalone LTE Broadcast system due to the lack ofsynchronization signals.

For example, aspects of the present disclosure propose techniques toassist with synchronization in a standalone LTE Broadcast system. Forexample, this may involve time division multiplexing (TDM) a lowperiodicity unicast burst of subframes within a broadcast transmissionthat allows for the use of legacy LTE PSS/SSS to aid in synchronizingthe LTE broadcast channel. According to aspects, these unicast subframesmay be transmitted occasionally by a base station with a low periodicityand may comprise PSS/SSS and Physical broadcast channel (PBCH)synchronization signals. According to certain aspects, this techniqueallows the majority of the traffic to remain LTE broadcasttransmissions, however, at the expense of a slower channelsynchronization time. A user equipment (UE) may receive the PSS/SSS/PBCHand synchronize operation accordingly.

The techniques described herein may be used for various wirelesscommunication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA andother networks. The terms “network” and “system” are often usedinterchangeably. A CDMA network may implement a radio technology such asuniversal terrestrial radio access (UTRA), cdma2000, etc. UTRA includeswideband CDMA (WCDMA), time division synchronous CDMA (TD-SCDMA), andother variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856standards. A TDMA network may implement a radio technology such asglobal system for mobile communications (GSM). An OFDMA network mayimplement a radio technology such as evolved UTRA (E-UTRA), ultra mobilebroadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20,Flash-OFDM®, etc. UTRA and E-UTRA are part of universal mobiletelecommunication system (UMTS). 3GPP Long Term Evolution (LTE) andLTE-Advanced (LTE-A), in both frequency division duplex (FDD) and timedivision duplex (TDD), are new releases of UMTS that use E-UTRA, whichemploys OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA,UMTS, LTE, LTE-A and GSM are described in documents from an organizationnamed “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB aredescribed in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). The techniques described herein may beused for the wireless networks and radio technologies mentioned above aswell as other wireless networks and radio technologies. For clarity,certain aspects of the techniques are described below forLTE/LTE-Advanced, and LTE/LTE-Advanced terminology is used in much ofthe description below. LTE and LTE-A are referred to generally as LTE.

Some examples of UEs may include cellular phones, smart phones, personaldigital assistants (PDAs), wireless modems, handheld devices, tablets,laptop computers, netbooks, smartbooks, ultrabooks, medical device orequipment, biometric sensors/devices, wearable devices (smart watches,smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g.,smart ring, smart bracelet)), an entertainment device (e.g., a music orvideo device, or a satellite radio), a vehicular component or sensor,smart meters/sensors, industrial manufacturing equipment, a globalpositioning system device, or any other suitable device that isconfigured to communicate via a wireless or wired medium. Some UEs maybe considered evolved or enhanced machine-type communication (eMTC) UEs.MTC and eMTC UEs include, for example, robots, drones, remote devices,such as sensors, meters, monitors, location tags, etc., that maycommunicate with a base station, another device (e.g., remote device),or some other entity. A wireless node may provide, for example,connectivity for or to a network (e.g., a wide area network such asInternet or a cellular network) via a wired or wireless communicationlink.

It is noted that while aspects may be described herein using terminologycommonly associated with 3G and/or 4G wireless technologies, aspects ofthe present disclosure can be applied in other generation-basedcommunication systems, such as 5G and later.

Example Wireless Communications Network

FIG. 1 illustrates an example wireless communications network 100, inwhich aspects of the present disclosure may be practiced. Techniquespresented herein may be used for transmission/reception ofsynchronization signals in an long term evolution (LTE) Broadcastsystem, according to certain aspects. For example, eNB 110 may transmit,within anchor subframes occurring at a first periodicity,synchronization signals of a first type, provide an indication of one ormore unicast subframes scheduled to occur between anchor subframes, andprovide an indication of one or more broadcast subframes scheduled tooccur between anchor subframes. A user equipment (UE) 120 may monitor,within anchor subframes occurring at a first periodicity, forsynchronization signals of a first type, obtain an indication of one ormore unicast subframes scheduled to occur between anchor subframes, andobtain an indication of one or more broadcast subframes scheduled tooccur between anchor subframes. The UE may then receive the one or moreunicast subframes and one or more broadcast subframes based on theobtained indications, and synchronize its operation to the networkaccordingly, as described in greater detail below.

According to aspects, an eNB may provide communication coverage for amacro cell, a pico cell, a femto cell, and/or other types of cell. Amacro cell may cover a relatively large geographic area (e.g., severalkilometers in radius) and may allow unrestricted access by UEs withservice subscription. A pico cell may cover a relatively smallgeographic area and may allow unrestricted access by UEs with servicesubscription. A femto cell may cover a relatively small geographic area(e.g., a home) and may allow restricted access by UEs having associationwith the femto cell (e.g., UEs in a closed subscriber group (CSG)). AneNB for a macro cell may be referred to as a macro eNB. An eNB for apico cell may be referred to as a pico eNB. An eNB for a femto cell maybe referred to as a femto eNB or a home eNB (HeNB). In the example shownin FIG. 1, an eNB 110 a may be a macro eNB for a macro cell 102 a, aneNB 110 b may be a pico eNB for a pico cell 102 b, and an eNB 110 c maybe a femto eNB for a femto cell 102 c. An eNB may support one ormultiple (e.g., three) cells. The terms “eNB”, “base station” and “cell”may be used interchangeably herein.

Wireless communications network 100 may also include relay stations. Arelay station is an entity that can receive a transmission of data froman upstream station (e.g., an eNB or a UE) and send a transmission ofthe data to a downstream station (e.g., a UE or an eNB). A relay stationmay also be a UE that can relay transmissions for other UEs. In theexample shown in FIG. 1, a relay station 110 d may communicate withmacro eNB 110 a and a UE 120 d in order to facilitate communicationbetween eNB 110 a and UE 120 d. A relay station may also be referred toas a relay eNB, a relay base station, a relay, etc.

Wireless communications network 100 may be a heterogeneous network thatincludes eNBs of different types, e.g., macro eNBs, pico eNBs, femtoeNBs, relay eNBs, etc. These different types of eNBs may have differenttransmit power levels, different coverage areas, and different impact oninterference in wireless communications network 100. For example, macroeNBs may have a high transmit power level (e.g., 5 to 40 Watts) whereaspico eNBs, femto eNBs, and relay eNBs may have lower transmit powerlevels (e.g., 0.1 to 2 Watts).

A network controller 130 may couple to a set of eNBs and may providecoordination and control for these eNBs. Network controller 130 maycommunicate with the eNBs via a backhaul. The eNBs may also communicatewith one another, e.g., directly or indirectly via a wireless orwireline backhaul.

UEs 120 (e.g., 120 a, 120 b, 120 c) may be dispersed throughout wirelesscommunications network 100, and each UE may be stationary or mobile. AUE may also be referred to as an access terminal, a terminal, a mobilestation, a subscriber unit, a station, etc. A UE may be a cellular phone(e.g., a smart phone), a personal digital assistant (PDA), a wirelessmodem, a wireless communication device, a handheld device, a laptopcomputer, a cordless phone, a wireless local loop (WLL) station, atablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook,etc. In FIG. 1, a solid line with double arrows indicates desiredtransmissions between a UE and a serving eNB, which is an eNB designatedto serve the UE on the downlink and/or uplink. A dashed line with doublearrows indicates potentially interfering transmissions between a UE andan eNB.

FIG. 2 shows a block diagram of a design of base station/eNB 110 and UE120, which may be one of the base stations/eNBs and one of the UEs inFIG. 1. Base station 110 may be equipped with T antennas 234 a through234 t, and UE 120 may be equipped with R antennas 252 a through 252 r,where in general T≥1 and R≥1.

At base station 110, a transmit processor 220 may receive data from adata source 212 for one or more UEs, select one or more modulation andcoding schemes (MCS) for each UE based on CQIs received from the UE,process (e.g., encode and modulate) the data for each UE based on theMCS(s) selected for the UE, and provide data symbols for all UEs.Transmit processor 220 may also process system information (e.g., forSRPI, etc.) and control information (e.g., CQI requests, grants, upperlayer signaling, etc.) and provide overhead symbols and control symbols.Processor 220 may also generate reference symbols for reference signals(e.g., the CRS) and synchronization signals (e.g., the PSS and SSS). Atransmit (TX) multiple-input multiple-output (MIMO) processor 230 mayperform spatial processing (e.g., precoding) on the data symbols, thecontrol symbols, the overhead symbols, and/or the reference symbols, ifapplicable, and may provide T output symbol streams to T modulators(MODs) 232 a through 232 t. Each modulator 232 may process a respectiveoutput symbol stream (e.g., for OFDM, etc.) to obtain an output samplestream. Each modulator 232 may further process (e.g., convert to analog,amplify, filter, and upconvert) the output sample stream to obtain adownlink signal. T downlink signals from modulators 232 a through 232 tmay be transmitted via T antennas 234 a through 234 t, respectively.

At UE 120, antennas 252 a through 252 r may receive the downlink signalsfrom base station 110 and/or other base stations and may providereceived signals to demodulators (DEMODs) 254 a through 254 r,respectively. Each demodulator 254 may condition (e.g., filter, amplify,downconvert, and digitize) its received signal to obtain input samples.Each demodulator 254 may further process the input samples (e.g., forOFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtainreceived symbols from all R demodulators 254 a through 254 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 258 may process (e.g., demodulateand decode) the detected symbols, provide decoded data for UE 120 to adata sink 260, and provide decoded control information and systeminformation to a controller/processor 280. A channel processor maydetermine RSRP, RSSI, RSRQ, CQI, etc.

On the uplink, at UE 120, a transmit processor 264 may receive andprocess data from a data source 262 and control information (e.g., forreports comprising RSRP, RSSI, RSRQ, CQI, etc.) fromcontroller/processor 280. Processor 264 may also generate referencesymbols for one or more reference signals. The symbols from transmitprocessor 264 may be precoded by a TX MIMO processor 266 if applicable,further processed by modulators 254 a through 254 r (e.g., for SC-FDM,OFDM, etc.), and transmitted to base station 110. At base station 110,the uplink signals from UE 120 and other UEs may be received by antennas234, processed by demodulators 232, detected by a MIMO detector 236 ifapplicable, and further processed by a receive processor 238 to obtaindecoded data and control information sent by UE 120. Processor 238 mayprovide the decoded data to a data sink 239 and the decoded controlinformation to controller/processor 240. Base station 110 may includecommunication unit 244 and communicate to network controller 130 viacommunication unit 244. Network controller 130 may include communicationunit 294, controller/processor 290, and memory 292.

Controllers/processors 240 and 280 may direct the operation at basestation 110 and UE 120, respectively, to perform techniques presentedherein for defining narrowband regions for enhanced machine typecommunication (eMTC) to use for communications between a UE (e.g., aneMTC UE) and a base station (e.g., an eNodeB). For example, processor240 and/or other processors and modules at base station 110, andprocessor 280 and/or other processors and modules at UE 120, may performor direct operations of base station 110 and UE 120, respectively. Forexample, controller/processor 280 and/or other controllers/processorsand modules at UE 120, and controller/processor 240 and/or othercontrollers/processors and modules at BS 110 may perform or directoperations 600 and 700 shown in FIGS. 6 and 7, respectively. Memories242 and 282 may store data and program codes for base station 110 and UE120, respectively. A scheduler 246 may schedule UEs for datatransmission on the downlink and/or uplink.

FIG. 3 shows an exemplary frame structure 300 for FDD in LTE. Thetransmission timeline for each of the downlink and uplink may bepartitioned into units of radio frames. Each radio frame may have apredetermined duration (e.g., 10 milliseconds (ms)) and may bepartitioned into 10 subframes with indices of 0 through 9. Each subframemay include two slots. Each radio frame may thus include 20 slots withindices of 0 through 19. Each slot may include L symbol periods, e.g.,seven symbol periods for a normal cyclic prefix (as shown in FIG. 3) orsix symbol periods for an extended cyclic prefix. The 2L symbol periodsin each subframe may be assigned indices of 0 through 2L−1.

In LTE, an eNB may transmit a primary synchronization signal (PSS) and asecondary synchronization signal (SSS) on the downlink in the center ofthe system bandwidth for each cell supported by the eNB. The PSS and SSSmay be transmitted in symbol periods 6 and 5, respectively, in subframes0 and 5 of each radio frame with the normal cyclic prefix, as shown inFIG. 3. The PSS and SSS may be used by UEs for cell search andacquisition. The eNB may transmit a cell-specific reference signal (CRS)across the system bandwidth for each cell supported by the eNB. The CRSmay be transmitted in certain symbol periods of each subframe and may beused by the UEs to perform channel estimation, channel qualitymeasurement, and/or other functions. The eNB may also transmit aphysical broadcast channel (PBCH) in symbol periods 0 to 3 in slot 1 ofcertain radio frames. The PBCH may carry some system information. TheeNB may transmit other system information such as system informationblocks (SIBs) on a physical downlink shared channel (PDSCH) in certainsubframes. The eNB may transmit control information/data on a physicaldownlink control channel (PDCCH) in the first B symbol periods of asubframe, where B may be configurable for each subframe. The eNB maytransmit traffic data and/or other data on the PDSCH in the remainingsymbol periods of each subframe.

FIG. 4 shows two exemplary subframe formats 410 and 420 with the normalcyclic prefix. The available time frequency resources may be partitionedinto resource blocks. Each resource block may cover 12 subcarriers inone slot and may include a number of resource elements. Each resourceelement may cover one subcarrier in one symbol period and may be used tosend one modulation symbol, which may be a real or complex value.

Subframe format 410 may be used for two antennas. A CRS may betransmitted from antennas 0 and 1 in symbol periods 0, 4, 7 and 11. Areference signal is a signal that is known a priori by a transmitter anda receiver and may also be referred to as pilot. A CRS is a referencesignal that is specific for a cell, e.g., generated based on a cellidentity (ID). In FIG. 4, for a given resource element with label Ra, amodulation symbol may be transmitted on that resource element fromantenna a, and no modulation symbols may be transmitted on that resourceelement from other antennas. Subframe format 420 may be used with fourantennas. A CRS may be transmitted from antennas 0 and 1 in symbolperiods 0, 4, 7 and 11 and from antennas 2 and 3 in symbol periods 1 and8. For both subframe formats 410 and 420, a CRS may be transmitted onevenly spaced subcarriers, which may be determined based on cell ID.CRSs may be transmitted on the same or different subcarriers, dependingon their cell IDs. For both subframe formats 410 and 420, resourceelements not used for the CRS may be used to transmit data (e.g.,traffic data, control data, and/or other data).

The PSS, SSS, CRS and PBCH in LTE are described in 3GPP TS 36.211,entitled “Evolved Universal Terrestrial Radio Access (E-UTRA); PhysicalChannels and Modulation,” which is publicly available.

An interlace structure may be used for each of the downlink and uplinkfor FDD in LTE. For example, Q interlaces with indices of 0 through Q−1may be defined, where Q may be equal to 4, 6, 8, 10, or some othervalue. Each interlace may include subframes that are spaced apart by Qframes. In particular, interlace q may include subframes q, q+Q, q+2Q,etc., where q∈{0, . . . , Q−1}.

The wireless network may support hybrid automatic retransmission request(HARQ) for data transmission on the downlink and uplink. For HARQ, atransmitter (e.g., an eNB) may send one or more transmissions of apacket until the packet is decoded correctly by a receiver (e.g., a UE)or some other termination condition is encountered. For synchronousHARQ, all transmissions of the packet may be sent in subframes of asingle interlace. For asynchronous HARQ, each transmission of the packetmay be sent in any subframe.

A UE may be located within the coverage of multiple eNBs. One of theseeNBs may be selected to serve the UE. The serving eNB may be selectedbased on various criteria such as received signal strength, receivedsignal quality, pathloss, etc. Received signal quality may be quantifiedby a signal-to-noise-and-interference ratio (SINR), or a referencesignal received quality (RSRQ), or some other metric. The UE may operatein a dominant interference scenario in which the UE may observe highinterference from one or more interfering eNBs.

An evolved Multimedia Broadcast and Multicast Service (eMBMS) in aMultimedia Broadcast Single Frequency Network (MBSFN) may be formed bythe eNBs in a cell to form a MBSFN area. eNBs may be associated withmultiple MBSFN areas, for example, up to a total of eight MBSFN areas.Each eNB in an MBSFN area synchronously transmits the same eMBMS controlinformation and data.

Each area may support broadcast, multicast, and unicast services. Aunicast service is a service intended for a specific user, e.g., a voicecall. A multicast service is a service that may be received by a groupof users, e.g., a subscription video service. A broadcast service is aservice that may be received by all users, e.g., a news broadcast. Thusa first MBSFN area may support a first eMBMS broadcast service, such asby providing a particular news broadcast to UE and a second MBSFN areamay support a second eMBMS broadcast service, such as by providing adifferent news broadcast to second UE.

Each MBSFN area supports a plurality of physical multicast channels(PMCH) (e.g., 15 PMCHs). Each PMCH corresponds to a multicast channel(MCH). Each MCH can multiplex a plurality (e.g., 29) of multicastlogical channels. Each MBSFN area may have one multicast control channel(MCCH). As such, one MCH may multiplex one MCCH and a plurality ofmulticast traffic channels (MTCHs) and the remaining MCHs may multiplexa plurality of MTCHs. The subframes configured to carry the MBSFNinformation can vary depending on the diversity mode of the cell. Ingeneral, MBSFN can be carried in all subframes except those onlyavailable for DL to the UE and special subframes. For example, where thecell is configured for FDD, MBSFN may be configured in all subframesexcept 0, 4, 5, and 9. For TDD operations, MBSFN may be configured inall subframes except 0, 1, 5, and 6.

FIG. 5 illustrates various components that may be utilized in a wirelessdevice 502 that may be employed within the wireless communicationnetwork 100 illustrated in FIG. 1. The wireless device 502 is an exampleof a device that may be configured to implement the various methodsdescribed herein. The wireless device 502 may be a base station 110 orany of the wireless nodes (e.g., 120). For example, the wireless device502 may be configured to perform operations 600 and/or 700 described inFIGS. 6 and 7, respectively (as well as other operations describedherein).

The wireless device 502 may include a processor 504 that controlsoperation of the wireless device 502. The processor 504 may also bereferred to as a central processing unit (CPU). Memory 506, which mayinclude both read-only memory (ROM) and random access memory (RAM),provides instructions and data to the processor 504. A portion of thememory 506 may also include non-volatile random access memory (NVRAM).The processor 504 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 506. Theinstructions in the memory 506 may be executable to implement themethods described herein, for example, to allow a UE to transmit dataefficiently during a connectionless access. Some non-limiting examplesof the processor 504 may include Snapdragon processor, applicationspecific integrated circuits (ASICs), programmable logic, etc.

The wireless device 502 may also include a housing 508 that may includea transmitter 510 and a receiver 512 to allow transmission and receptionof data between the wireless device 502 and a remote location. Thetransmitter 510 and receiver 512 may be combined into a transceiver 514.A single transmit antenna or a plurality of transmit antennas 516 may beattached to the housing 508 and electrically coupled to the transceiver514. The wireless device 502 may also include (not shown) multipletransmitters, multiple receivers, and multiple transceivers. Thewireless device 502 can also include wireless battery chargingequipment.

The wireless device 502 may also include a signal detector 518 that maybe used in an effort to detect and quantify the level of signalsreceived by the transceiver 514. The signal detector 518 may detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 302 may alsoinclude a digital signal processor (DSP) 520 for use in processingsignals.

The various components of the wireless device 502 may be coupledtogether by a bus system 522, which may include a power bus, a controlsignal bus, and a status signal bus in addition to a data bus. Theprocessor 504 may be configured to access instructions stored in thememory 506 to perform connectionless access, in accordance with aspectsof the present disclosure discussed below.

Example Synchronization for Standalone LTE Broadcast

In LTE, a carrier was introduced for the purpose of transmitting LTEMultimedia Broadcast Multicast Service (MBMS) data. Additionally, aBroadcast-only LTE subframe was previously defined, which comprises nophysical downlink control channel (PDCCH) (i.e., the control channel wasremoved from the Broadcast-only LTE subframe) and little or no unicasttraffic (i.e., all or a majority of subframes are configured asBroadcast-only). The LTE MBMS carrier is a standalone carrier, meaningbroadcast functionality including synchronization, channel setup, andbroadcast data reception must be done within that single MBMS carrier.That is, there is no aid from an anchor primary cell for synchronizationor control information for the MBMS carrier.

In the current eMBMS structure, synchronization signals may be presentevery 5 ms. For example, subframes 0 and 5 are guaranteed to be unicastsuch that a primary synchronization signal (PSS)/secondarysynchronization signal (SSS) can be transmitted. However, conversion ofthese subframes (i.e., subframes 0 and 5 carrying PSS and SSS) toBroadcast-only subframes eliminates synchronization capabilities basedon the PSS and SSS.

Thus, aspects of the present disclosure provide techniques for alievingthe issue with synchronization in a standalone LTE Broadcast system dueto the lack of synchronization signals for standalone LTE broadcast. Forexample, one potential method to assist with synchronization in astandalone LTE Broadcast system may be to generate modified PSS and SSSsignals (e.g., PSS_(broadcast), SSS_(broadcast) signals). According tocertain aspects, the PSS_(broadcast), SSS_(broadcast) signals may betransmitted by a base station within a broadcast subframe in a systemnumber (SFN) configuration (i.e., multiple cells transmit samesynchronization sequences). However, there may be a few draw backsassociated with modifying the PSS/SSS signals. For example, thePSS_(broadcast) and SSS_(broadcast) signals may increase signalingoverhead and may consume resources that should be allocated to Broadcastdata. Further, these signals may not be the same as legacy PSS/SSS. Forexample, the numerology of standalone LTE Broadcast subframe (e.g.,symbol and CP duration, tone spacing, pilot placement) may be verydifferent from legacy unicast. With these large differences betweenbroadcast and unicast versions of the synchronization signals, a new setof synchronization reception procedures may be required.

Another method to assist with synchronization in a standalone LTEBroadcast system may involve time division multiplexing (TDM) a lowperiodicity unicast burst of subframes within a broadcast transmissionthat allows for the use of legacy LTE PSS/SSS to aid in synchronizingthe LTE broadcast channel. As noted, these unicast subframes may betransmitted occasionally with a low periodicity (e.g., 80 ms or 160 ms)and may comprise PSS/SSS and Physical broadcast channel (PBCH)synchronization signals. According to certain aspects, this techniqueallows the majority of the traffic to remain LTE broadcasttransmissions, however, at the expense of a slower channelsynchronization time.

FIG. 6 illustrates example operations 600 for wireless communications.According to certain aspects, operations 600 may be performed, forexample, by a base station (e.g., eNB 110).

Operations 600 begin at 602 by transmitting, within anchor subframesoccurring at a first periodicity, synchronization signals of a firsttype. At 604, the base station provides an indication of one or moreunicast subframes scheduled to occur between anchor subframes. At 606,the base station provides an indication of one or more broadcastsubframes scheduled to occur between anchor subframes.

FIG. 7 illustrates example operations 700 for wireless communications.According to certain aspects, operations 700 may be performed, forexample, by a user equipment (e.g., UE 120).

Operations 700 begin at 702 by monitoring, within anchor subframesoccurring at a first periodicity, for synchronization signals of a firsttype. At 704, the UE obtains an indication of one or more unicastsubframes scheduled to occur between anchor subframes. At 706, the UEobtains an indication of one or more broadcast subframes scheduled tooccur between anchor subframes. According to certain aspects, the UE mayobtain both indications via, for example, one or more antennas 252.While not shown, operations 700 may also include the UE receiving theone or more unicast subframes and one or more broadcast subframes.

As noted above, to help alleviate the issue of synchronization in astandalone LTE Broadcast system, one or more legacy subframes may betransmitted with a low periodicity for the purpose of channelsynchronization. According to certain aspects, these legacy subframesmay be denoted as anchor subframes and may be transmitted with aspecific pre-defined periodicity (e.g., 80 ms or 160 ms). Additionally,the anchor subframe(s) may carry the PSS/SSS signals, which may betransmitted by a base station in known symbols within the subframe(s).For example, the PSS/SSS signals for broadcast synchronization may usethe same assignment as legacy PSS/SSS signals. For example, forfrequency division duplexing, the PSS may occupy the center 62 toneswithin the last symbol of the first slot of the anchor subframe and theSSS may occupy the center 62 within the penultimate symbol of the firstslot of the anchor subframe. Additionally, for example, for timedivision duplexing (TDD), the PSS may occupy the center 62 tones withinthe third symbol of the first slot of the second anchor subframe and theSSS may occupy the center 62 within the last symbol of the second slotof the first anchor subframe. While specific tone/symbol locations areprovided, it should be understood that the PSS/SSS tone/symbols may belocated anywhere within the anchor subframe.

According to certain aspects, the PBCH may also be transmitted by thebase station within the anchor subframe in a pre-known resourceallocation. For example, the PBCH may be transmitted in a similar manneras a legacy PBCH (i.e., non-standalone LTE broadcast), for example, inthe center 72 tones of the first four symbols within the second slot ofthe anchor subframe. Likewise, while specific tone/symbol locations areprovided, it should be understood that the PBCH tone/symbols may belocated anywhere within the anchor subframe.

Additionally, according to certain aspects, using PDCCH grants, a basestation may transmit system information block (SIB) information andunicast PDSCH data within the anchor subframe as well as any additionalsubframes that are allocated as unicast subframes, which are describedin greater detail below.

FIG. 8 illustrates an example subframe transmission format for LTEstandalone broadcast. As illustrated, an anchor subframe (e.g., denoted“A”) may be transmitted first and may contain PSS/SSS, PBCH, physicaldownlink control channel (PDCCH)-based scheduling of SIBs, andPDCCH-based scheduling of unicast transmissions (e.g., indicating anumber of unicast subframes that will be transmitted after the anchorsubframe). According to certain aspects, the transmission periodicity ofthe anchor subframe (e.g., 80-160 ms) may be aligned with a radio frame,as illustrated. After the anchor subframe is transmitted by the basestation, it may be followed by a number (e.g., as indicated by thescheduling information in the anchor subframe) of unicast subframes(e.g., denoted “U”), which may contain repetitions of the PSS/SSS and/orPBCH and PDCCH-based scheduling for SIBs transmitted in the anchorsubframes, as well as unicast transmissions/data. According to certainaspects, the duration of the unicast region may be defined in a masterinformation block transmitted by the base station and monitored for bythe UE. Additionally, as illustrated, following the unicast subframes, anumber of broadcast subframes (e.g., denoted “B”) may be transmitted.The broadcast subframes may not have a PDCCH allocation and may have alarge cyclic prefix (CP). According to aspects, the broadcast subframesmay contain broadcast data, such as (e)MBMS data.

According to certain aspects, for successful reception of the unicastand broadcast subframes, the MIB transmitted by the base station mayneed to contain information indicating when unicast and broadcastsubframes (e.g., the unicast and broadcast subframes illustrated in FIG.8) are scheduled. For example, the MIB may comprise an indication of thesystem bandwidth, the system frame number, and the subframe pattern ofthe unicast subframe and broadcast subframe transmissions. Additionally,for TDD, the MIB may comprise the DL/UL configuration for the unicastregion, for example, as explained in greater detail below. According tocertain aspects, upon reception of the MIB, the UE may determine theunicast subframe locations (e.g., for reception of additional SIBinformation and unicast traffic) as well Broadcast subframe locationsand monitor for and receive/obtain these subframes within the determinedlocations

According to certain aspects, repetition of the PSS/SSS synchronizationsignals as well as the PBCH may be required (e.g., similar to a legacysystem), for example, to reach acceptable synchronization andacquisition performance metrics. For example, a known fixed number ofrepetitions of the PSS/SSS and PBCH may be allowed with known subframeperiodicity between the first anchor subframe and its repetitions. Forexample, with reference to FIG. 8, a fixed number of repetitions of thePSS/SSS and PBCH (e.g., transmitted within unicast subframes) may beallowed between a first transmission 802 of the anchor subframe and asecond (repeated) transmission 804 of the anchor subframe.

In some cases, the number of repetitions for each of PSS, SSS, and/orPBCH may vary independently, for example, to meet a performancerequirement. According to certain aspects, upon reception of the MIB,the UE may know the exact configuration and allocation of PSS/SSS andPBCH instances/repetitions and modify its receiver algorithmaccordingly, for example, to improve reception performance. That is, theUE may modify its receiver algorithm in order to monitor for and receivethe PSS/SSS/PBCH repetitions to improve reception performance.

In addition to receiving the MIB, the UE may acquire one or more SIBtransmissions, which may be transmitted by the base station in theanchor and unicast subframes, for example, as illustrated in FIG. 8.According to certain aspects, the SIB transmission(s) may be scheduledby the base station via a PDCCH grant (e.g., transmitted in the anchorsubframe), and for each SIB (e.g., SIB1-SIB17), a different periodicitymay be scheduled, which may be in multiples of the anchor subframeperiodicity. For example, SIB1 may be scheduled within each transmissionof the anchor subframe, whereas SIB3 may be scheduled every othertransmission of the anchor subframe.

Additionally, the anchor subframe(s) and/or unicast subframes may beused by the base station to transmit other types of signals. Forexample, the base station may use the anchor subframe(s) and/or unicastsubframes transmit legacy eMBMS broadcast signals, Single Cell-Point toMultipoint (SC-PTM) signals, and/or a Lean Carrier-New Carrier Type(NC). In some cases, subscription information or authentication/keyinformation may be sent to specific users or groups of users in theseunicast subframes (e.g., acting as a side channel).

Aspects presented below provide more detail for a TDD implementation ofstandalone LTE broadcast synchronization. For example, according tocertain aspects, after decoding the anchor subframe, a UE may know DL/ULconfiguration of unicast subframes based on the indication provided bythe base station DL/UL subframe indication, as noted above. For example,the UE may know the configurable number of DL subframes followed by aspecial subframe, which can include a DL portion, Guard interval, and ULportion, followed by a configurable number of UL subframes. This set ofsubframes may then followed by the broadcast portion.

Additionally, within the UL portion of the unicast region, the basestation may signal, on a per cell basis, that a configurable number ofuplink subframes maybe be converted to DL broadcast subframe and maydynamically switch on each anchor subframe period based on broadcastloading. In other words, if a threshold amount of broadcast data needsto be transmitted, the base station may indicate to the UE that certainUL unicast subframes will be converted to broadcast subframes. The UEmay reconfigure its reception algorithm accordingly to receive theadditional broadcast data. According to certain aspects, this may besimilar to LTE TDD enhanced interference mitigation and trafficadaptation (eIMTA), where subframe configurations may be dynamicallychanged based on a traffic load.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “identifying” encompasses a wide variety ofactions. For example, “identifying” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “identifying” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“identifying” may include resolving, selecting, choosing, establishingand the like.

In some cases, rather than actually communicating a frame, a device mayhave an interface to communicate a frame for transmission or reception.For example, a processor may output a frame, via a bus interface, to anRF front end for transmission. Similarly, rather than actually receivinga frame, a device may have an interface to obtain a frame received fromanother device. For example, a processor may obtain (or receive) aframe, via a bus interface, from an RF front end for transmission.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software/firmwarecomponent(s) and/or module(s), including, but not limited to a circuit,an application specific integrated circuit (ASIC), or processor.Generally, where there are operations illustrated in figures, thoseoperations may have corresponding counterpart means-plus-functioncomponents.

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software/firmwarecomponent(s) and/or module(s), including, but not limited to a circuit,an application specific integrated circuit (ASIC), or processor.Generally, where there are operations illustrated in Figures, thoseoperations may be performed by any suitable corresponding counterpartmeans-plus-function components.

For example, means for transmitting, means for retransmitting, means forsending, and/or means for providing may comprise a transmitter, whichmay include the transmit processor 220, the TX MIMO processor 230, themodulator(s) 232 a-232 t, and/or antenna(s) 234 a-234 t of the basestation 110 illustrated in FIG. 2; the transmit processor 264, the TXMIMO processor 266, the modulator(s) 254 a-254 r, and/or antenna(s) 252a-252 r of the user equipment 120 illustrated in FIG. 2; and/or thetransmitter 510, DSP 520, and/or antenna(s) 516 of the wireless device502 illustrated in FIG. 5.

Means for receiving and/or means for obtaining may comprise a receiver,which may include the receive processor 238, the MIMO detector 236, thedemodulator(s) 232 a-232 t, and/or antenna(s) 234 a-234 t of the basestation 110 illustrated in FIG. 2; the receive processor 258, the MIMOdetector 256, the demodulator(s) 254 a-254 r, and/or antenna(s) 252a-252 r of the user equipment 120 illustrated in FIG. 2; and/or thereceiver 512, DSP 520, signal detector 518, and/or antenna(s) 516 of thewireless device 502 illustrated in FIG. 5.

Means for determining, means for performing, means for monitoring maycomprise a processing system, which may include controller/processor 240and/or the other processors of the base station 110 illustrated in FIG.2; the controller/processor 280 and/or other processors of the userequipment 120 illustrates in FIG. 2; and/or the processor 504 of thewireless device 502 illustrated in FIG. 5.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or combinations thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, software/firmware, or combinations thereof. To clearlyillustrate this interchangeability of hardware and software/firmware,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware orsoftware/firmware depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in asoftware/firmware module executed by a processor, or in a combinationthereof. A software/firmware module may reside in RAM memory, flashmemory, ROM memory, EPROM memory, EEPROM memory, phase change memory,registers, hard disk, a removable disk, a CD-ROM, or any other form ofstorage medium known in the art. An exemplary storage medium is coupledto the processor such that the processor can read information from, andwrite information to, the storage medium. In the alternative, thestorage medium may be integral to the processor. The processor and thestorage medium may reside in an ASIC. The ASIC may reside in a userterminal. In the alternative, the processor and the storage medium mayreside as discrete components in a user terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software/firmware, or combinations thereof. Ifimplemented in software/firmware, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by ageneral purpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD/DVD or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code means in the form of instructions or datastructures and that can be accessed by a general-purpose orspecial-purpose computer, or a general-purpose or special-purposeprocessor. Also, any connection is properly termed a computer-readablemedium. For example, if the software/firmware is transmitted from awebsite, server, or other remote source using a coaxial cable, fiberoptic cable, twisted pair, digital subscriber line (DSL), or wirelesstechnologies such as infrared, radio, and microwave, then the coaxialcable, fiber optic cable, twisted pair, DSL, or wireless technologiessuch as infrared, radio, and microwave are included in the definition ofmedium. Disk and disc, as used herein, includes compact disc (CD), laserdisc, optical disc, digital versatile disc (DVD), floppy disk andBlu-ray disc where disks usually reproduce data magnetically, whilediscs reproduce data optically with lasers. Combinations of the aboveshould also be included within the scope of computer-readable media.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method for wireless communications by a userequipment (UE), comprising: monitoring within anchor subframes of aplurality of radio frames for synchronization signals of a first type,wherein the anchor subframes occur at a first periodicity; receiving amaster information block (MIB) based on the monitored anchor subframes;and obtaining, from the MIB, an indication of one or more unicastsubframes and one or more broadcast subframes scheduled to occur betweenthe anchor subframes, wherein the one or more broadcast subframes aremultimedia broadcast multicast service (MBMS) subframes.
 2. The methodof claim 1, wherein the first periodicity corresponds to a multiple of aradio frame periodicity.
 3. The method of claim 1, further comprisingcombining synchronization signals received in multiple of the one ormore unicast subframes.
 4. The method of claim 1, wherein thesynchronization signals monitored for in the one or more unicastsubframes are of a second type different than the first type.
 5. Themethod of claim 1, further comprising obtaining an indication of whichof the one or more unicast subframes are for downlink transmissions andwhich are for uplink transmissions.
 6. The method of claim 1, furthercomprising receiving a physical broadcast channel (PBCH) within one ormore of the anchor subframes.
 7. The method of claim 1, furthercomprising receiving system information block (SIB) information withinat least one of: one or more of the anchor subframes; or the one or moreunicast subframes.
 8. The method of claim 1, further comprisingreceiving unicast physical downlink shared channel (PDSCH) data withinat last one of: one or more of the anchor subframes; or the one or moreunicast subframes.
 9. The method of claim 1, wherein at least one of theanchor subframes or the one or more unicast subframes comprise at leastone of: legacy eMBMS broadcast signals; Single Cell-point to Multipoint(SC-PTM) signals; or a new carrier type (NCT).
 10. The method of claim1, wherein the anchor subframes comprise information for the UE toreceive the one or more unicast subframes and the one or more broadcastsubframes.
 11. The method of claim 10, wherein the information for theUE to receive the one or more unicast subframes and the one or morebroadcast subframes comprises at least one of a system bandwidth, asystem frame number, a subframe pattern for the one or more unicastsubframes, or a subframe pattern for the one or more broadcastsubframes.
 12. The method of claim 1, wherein: each radio frame of theplurality of radio frames includes a majority of broadcast subframes;and the anchor subframes and the one or more unicast subframes compriselegacy subframes.
 13. The method of claim 1, wherein the synchronizationsignals in at least one of the one or more unicast subframes compriserepetitions of the synchronization signals of the first type in theanchor subframes.
 14. The method of claim 1, further comprising:receiving an indication that at least one unicast subframe of the one ormore unicast subframes will be converted to a broadcast subframe,wherein the indication is based, at least in part, on an amount ofbroadcast data being above a threshold; and receiving the broadcast datain the at least one converted unicast subframe.
 15. An apparatus forwireless communications by a user equipment (UE), comprising: at leastone processor configured to: monitor within anchor subframes of aplurality radio frames for synchronization signals of a first type,wherein the anchor subframes occur at a first periodicity; receive amaster information block (MIB) based on the monitored anchor subframes;and obtain, from the MIB, an indication of one or more unicast subframesand one or more broadcast subframes scheduled to occur between theanchor subframes, wherein the one or more broadcast subframes aremultimedia broadcast multicast service (MBMS) subframes; and a memorycoupled with the at least one processor.
 16. The apparatus of claim 15,wherein the first periodicity corresponds to a multiple of a radio frameperiodicity.
 17. The apparatus of claim 15, wherein the at least oneprocessor is further configured to combine synchronization signalsreceived in multiple of the one or more unicast subframes.
 18. Theapparatus of claim 15, wherein the synchronization signals monitored forin the one or more unicast subframe are of a second type different thanthe first type.
 19. The apparatus of claim 15, wherein the at least oneprocessor is further configured to obtain an indication of which of theone or more unicast subframes are for downlink transmissions and whichare for uplink transmissions.
 20. The apparatus of claim 15, wherein theat least one processor is further configured to receive a physicalbroadcast channel (PBCH) within one or more of the anchor subframes. 21.The apparatus of claim 15, wherein the at least one processor is furtherconfigured to receive system information block (SIB) information withinat least one of: one or more of the anchor subframes; or the one or moreunicast subframes.
 22. The apparatus of claim 15, wherein the at leastone processor is further configured to receive unicast physical downlinkshared channel (PDSCH) data within at last one of: one or more of theanchor subframes; or the one or more unicast subframes.
 23. Theapparatus of claim 15, wherein at least one of the anchor subframes orthe one or more unicast subframes comprise at least one of: legacy eMBMSbroadcast signals; Single Cell-point to Multipoint (SC-PTM) signals; ora new carrier type (NCT).
 24. The apparatus of claim 15, wherein theanchor subframes comprise information for the UE to receive the one ormore unicast subframes and the one or more broadcast subframes.
 25. Theapparatus of claim 24, wherein the information for the UE to receive theone or more unicast subframes and the one or more broadcast subframescomprises at least one of a system bandwidth, a system frame number, asubframe pattern for the one or more unicast subframes, or a subframepattern for the one or more broadcast subframes.
 26. An apparatus forwireless communications by a user equipment (UE), comprising: means formonitoring within anchor subframes of a plurality radio frames forsynchronization signals of a first type, wherein the anchor subframesoccur at a first periodicity; means for receiving a master informationblock (MIB) based on the monitored anchor subframes; and means forobtaining, from the MIB, an indication of one or more unicast subframesand one or more broadcast subframes scheduled to occur between theanchor subframes, wherein the one or more broadcast subframes aremultimedia broadcast multi service (MBMS) subframes.
 27. Anon-transitory computer-readable medium for wireless communications by auser equipment (UE), comprising instructions for: monitoring withinanchor subframes of a plurality radio frames for synchronization signalsof a first type, wherein the anchor subframes occur at a firstperiodicity; receiving a master information block (MIB) based on themonitored anchor subframes; and obtaining, from the MIB, an indicationof one or more unicast subframes and one or more broadcast subframesscheduled to occur between the anchor subframes, wherein the one or morebroadcast subframes are multimedia broadcast multicast service (MBMS)subframes.